FIG. 1 shows a conventional keyswitch structure, which comprises a key cap 10a, a guiding stage 11a and a rubber cone 12a. The cap 10a is a rectangular-shaped cover and has a rectangular frame 13a, which has four quarter-circle poles 14a on the four corners thereof. The guiding stage 11a is arranged on the keyboard panel 15a and has a rectangular guiding groove, or, 16a on top side thereof such that the four poles 14a are sildably fitted within the guiding groove 16a. The rubber cone 12a is received within the guiding groove 16a and is made of conductive rubber.
When the user presses down the cap 10a, the frame 13a is forced to move downward along the guiding groove 16a. At this time, the rubber cone 12a is collapsed such that the conductive edge (not shown) is in contact with the circuit under the panel 15a. A pulse signal is generated to response the pressing operation.
However, in the above-mentioned keyswitch, the cap 10a is supported by fitting the frame 13a thereof along the guiding groove 16a of the guiding stage 11a. The cap 10 a is unstable during operation. Moreover, the quarter-circle poles 14a of the frame 13a are in contact with the four inner corners of the guiding groove 16a. The contact area is relatively large such that the smooth movement of cap 10a may be hindered. Moreover, the upper end of the inner wall of the guiding groove 16a is square in profile such that the insertion of the frame 13a into the guiding groove 16a is difficult.
In one aspect of the invention, at least one guiding slot is arranged on the outer wall of the frame, and at least one guiding strip is arranged on the inner wall of the guiding groove to guide the movement of the frame and enhance stable displacement of the cap. Moreover, two slim flanges are provided on each corner of the frame to reduce the friction.
In another aspect of the invention, arc-shaped guiding surface, or taper, is provided on the upper inner wall of the guiding groove to guide the fame into the guiding groove.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: